It is sometimes important to be able to measure the amount of ice which results from cooling water to its freezing point. For this purpose, various types of sophisticated sonar, mass flow and radiation devices have been employed. These devices are not only expensive and complicated but of questionable reliability. The present invention fills a need by providing a simple method and inexpensive apparatus which can be used to determine the amount of ice produced by cooling water until it freezes, particularly with the ice in admixture with the liquid water phase, and especially as an ice slurry.